I have a sewer smell in the vicinity of my sump pump basin. The sump pump is less than 2 yrs. Old and is working. The lid that covers the sump pump and the sewer vent is caulked and sealed. I have poured water with bleach down the drains that flush into the sump pump basin. The pipes that attach to the sump pump and vent the sewer gas are made of PVC. There are no clogs anywhere in the house; yet, I still have a sewer smell. Could I have a blockage in the vent leading out of the roof and how can I tell? What's the normal procedure to fix it?

Yes, you can pour water down a sewer vent on the roof to check for blockage. If it is plugged, snaking it is the only real cure. However, I would bet that even though the sewer pit appears to be sealed, it may not be air tight. Can you post some pics of your sewer pit and piping?